private Image CreateImage(GeckoWebBrowser browser)
{
if (_syncControl.InvokeRequired)
{
return((Image)_syncControl.Invoke(new Func <GeckoWebBrowser, Image>(CreateImage), browser));
}
#if __MonoCS__
var offscreenBrowser = browser as OffScreenGeckoWebBrowser;
Debug.Assert(offscreenBrowser != null);
return(offscreenBrowser.GetBitmap(browser.Width, browser.Height));
#else
var creator = new ImageCreator(browser);
byte[] imageBytes = creator.CanvasGetPngImage((uint)browser.Width, (uint)browser.Height);
// Ensure image is still valid after the MemoryStream closes.
using (var stream = new MemoryStream(imageBytes))
{
using (var image = new Bitmap(stream))
{
return(new Bitmap((image)));
}
}
#endif
}
public void LinuxSend()
{
ImageCreator ic = new ImageCreator(geckoWebBrowser1);
// TODO: Clean and speed up this nonsense!
byte[] b = ic.CanvasGetPngImage(0, 0, (uint)geckoWebBrowser1.Width, (uint)geckoWebBrowser1.Height);
using (MemoryStream ms = new MemoryStream(b))
{
using (Image img = Image.FromStream(ms))
{
using (Bitmap bmp = new Bitmap(img, 800, 450))
{
MemoryStream res = new MemoryStream();
bmp.Save(res, ImageFormat.Png);
byte[] result = res.ToArray();
byte[] len = BitConverter.GetBytes((int)res.Length);
Program.STDOut.Write(len, 0, 4);
Program.STDOut.Write(result, 0, (int)res.Length);
Program.STDOut.Flush();
}
}
}
}
private Image CreateImage(GeckoWebBrowser browser, Color coverColor, int top, int bottom)
{
if (_syncControl.InvokeRequired)
{
return((Image)_syncControl.Invoke(new Func <GeckoWebBrowser, Color, int, int, Image>(CreateImage), browser,
coverColor, top, bottom));
}
// It's REALLY tricky to get the thumbnail created so that it reliably shows the image.
// See BL-4170 and then BL-6257. We tried all kinds of tricks to tell when the image is
// loaded into the document, such as checking image.completed and image.naturalWidth > 0
// and waiting for two cycles of window.requestAnimationFrame (which is supposed to cover
// starting and completing painting images) after the onload event fires. None of this
// helped appreciably. A 400ms delay was enough for most images on a fast desktop, but
// there was no way to tell how long would be enough on a slow laptop.
// So, we finally came up with this technique, which is to examine the actual bitmap
// that is produced to see whether there is something drawn in the image region of the
// page. Even that did not prove to be enough: it's quite possible (especially with a tall
// PNG image) for CanvasGetPngImage to return an image with the cover picture only partly
// drawn. Fortunately, it seems to consistently draw from the top down, so we can be pretty
// sure there is no more image to come if we do two cycles and there is no change in the
// last line that is drawn.
// On a typical tall PNG this loop has three iterations.
// image is partly drawn (~40ms); ~140ms to find last line
// image is fully drawn (~80ms); 1ms to find last line
// image is fully drawn again (~28ms); 1ms to find last line
// On a typical wide png, 2 iterations:
// ~40 to draw image, ~80 to find last line (and repeat)
// For jpg we seem to typically have three also:
// ~20ms to make image; ~200ms to determine nothing is there
// ~600ms to make image; ~40 to find last line
// ~120 to redraw; ~40 to find last line
while (true) // Exit when we settle on an image and return it.
{
var watch = new Stopwatch();
watch.Start();
int lastLineOfImage = -1;
while (true)
{
var creator = new ImageCreator(browser);
byte[] imageBytes = creator.CanvasGetPngImage((uint)browser.Width, (uint)browser.Height);
using (var stream = new MemoryStream(imageBytes))
{
using (var image = new Bitmap(stream))
{
if (watch.ElapsedMilliseconds > 5000)
{
// Maybe there's no image or it's color perfectly mathches the background?
// When we used to do this with a simple delay 400ms was usually enough;
// if we can't get it in 5s give up, and use whatever we've got.
watch.Stop();
Debug.WriteLine("returned possibly incomplete thumnail after more than 5000ms");
return(new Bitmap(image));
}
if (top < 0)
{
// no image to wait for, go with what we have.
return(new Bitmap(image));
}
// I'm not sure how top or bottom can get to be greater than image.Height, but if they do,
// it causes a crash. It makes no sense to look for the last line drawn beyond the end of the
// image, so if something tries, just start looking at the bottom.
var newLastLine = GetLastLineOfImage(coverColor, Math.Min(top, image.Height), Math.Min(bottom, image.Height), image);
// If nothing has been drawn yet, we want to keep trying until something is.
// If something has been drawn, we want to keep trying until a cycle when
// nothing more gets added.
if (newLastLine == -1 || newLastLine > lastLineOfImage)
{
lastLineOfImage = newLastLine;
// This is meant to give the browser more of a chance to load it.
// It may well have been working on it anyway in another thread
// while we were checking pixels. Not too sure about the best length
// for this delay; longer might mean less time wasted checking pixels,
// but the minimum delay is two times this interval, so we don't want
// it too long. 50ms, at least on my desktop, usually doesn't result
// in any wasted iterations, nor much delay.
Thread.Sleep(50);
continue; // try again
}
// No more image drawn than the last iteration, and we got something, so assume we have the whole thing.
watch.Stop();
Debug.WriteLine("Got image after waiting " + watch.ElapsedMilliseconds);
return(new Bitmap(image));
}
}
}
}
}
